This invention relates to metal working, and in particular, relates to a method for chemically milling and forming three-dimensional objects from sheet metal.
The traditional method for forming designs in metal objects from sheet metal has been through the use of large mechanical presses for stamping out the desired design. Such a method entailed expensive precision-machined molds and high labor costs in order to form the desired metal design. In addition to this high initial capital investment in the presses and tools, the tools were subject to wear, especially working with a material such as metal, thereby increasing the cost of production. The necessity for skilled labor for the set up and run for stamping out a particular design further increases the overall cost of this traditional method.
Therefore, an object of the subject invention is an improved and inexpensive method of forming a desired intricate pattern in sheet metal.
Another object of the subject invention is a method of chemical milling whereby a desired intricate pattern might be formed in sheet metal for the production of three-dimensional articles.
A still further object of the subject invention is an improved method of forming a three-dimensional article from sheet metal whereby substantially identical designs are etched on both sides of the sheet metal.
A still further object of the subject invention is an improved method of forming a three-dimensional article from sheet metal whereby substantially different designs are etched on both sides of the sheet metal.
A further object of the subject invention is an improved method of forming three-dimensional articles from sheet metal by selectively etching score lines in the design on one side of the sheet metal and not etching the same score lines on the opposite side of the sheet metal whereby the pattern thereby created may be folded along the score lines.
These and other objects are attained in accordance with the present invention, whereby metallic objects are manufactured having intricate patterns or designs, such as Christmas tree ornaments and other ornamental or functional metal pieces, by an improved process of chemical milling. In this process, articles of relatively thin metal are formed with openings in an intricate pattern to secure a design which may be either pleasing to the eye or functional. These articles may be made three-dimensional by selective folding along score lines and tabs formed by the inventive process, as will be described.
In the subject process, a chemical resist material is applied to a flat sheet of metal in the form of a desired design. The resist material is not applied to those areas which will formulate the design. This practice is well known and widely used in other arts such as screen printing and the like, and in fact, screen printing procedures may be used in the application of the resist materials. These resist materials are applied to both sides of the metal plate in identical design and placement, with exceptions as noted below. An etchant is applied to the plate in accordance with the desired design. This etchant solution will dissolve the metal at those areas on the metal plate where there is an absence of resist material, however, will not affect the plate where resist material has been applied. By placing the etchant on both sides of the plate, it will erode or dissolve the metal and form an opening in the plate in the desired design by virtue of the above-described selective placement of the resist material on the plate. After the eroded metal and resist are washed away, the metal may be reclaimed by processes well known in the art, if the object is formed from precious metals such as gold, silver or even copper.
In order to form the three-dimensional articles, the etched metal is folded along score lines, hyphenated lines, or tabs which are formed by the subject inventive method to achieve the three-dimensional appearance.
In one embodiment of the invention, the lines on which these articles are folded have been scored so as to allow an easy and accurate folding of the object along those lines. This scoring is accomplished through the selective placement of the resist material on one side only of the metal plate along the line which is to be scored, while on the opposite side of the plate, resist material is not placed on this score line. This selective placement of the resist material allows one side of the plate to become partially eroded on the application of the etchant solution to provide the score line. The placement of the resist material on the other side of the metal, as well as the control of the amount of etchant, assures that the metal plate will not be completely eroded on that line and, therefore, no opening will form. However, a score line is formed on which the metal may be folded.
In another embodiment of the subject invention, small tabs are formed through the above-identified method of selective placement of the resist material. The tabs connect selected areas of the design and allow the connected areas to be folded or twisted at the tabs to form the desired three-dimensional article. The tabs may be etched on one side if desired, but generally neither side of the tabs will be etched to achieve the strength necessary in the use of such a small area and support the metal portion being twisted out of the original plane of the metal. A plurality of tabs may also be used to achieve an effect similar to the score lines described above.